I dislike predicted pace charts simply because when I fall off my prediction one of 2 things happen. 1. I blow up trying to catch up. 2. I fall into a depression funk and slow down. Its much better for me to just run with how I feel and take what the day has to give.

Joe I so know that feeling of shutting down when the watch doesn't give you the feedback you were hoping/expecting to see. It can drain me emotionally even if I wasn't feeling so bad before I look at the watch. I guess it is just one more thing I'll have to prepare myself for prior to a race now.

All about predictive analytics and pace charts, but I make mine with 3-4 variables for fastest, expected, and slower. The key in the race however is to use your pace chart info on a short term level, not a race level. If you use it to focus on making that 24 (or 20 or 30 or whatever) hour self-imposed cutoff, then yes, as soon as you SLIGHTLY fall off it you get depressed and/or push yourself too hard to catch up and then blow up. Your body has optimal pace(s) throughout the race that will maximize your efficiency and minimize your finishing time. A rigid pace chart has no consideration for how your body is performing that day, the weather, your ankle sprain, etc.

I find the real value of well thought out pace charts is on an aid station-to-aid station level. Based on how I'm running, I know whether I'm in my faster, average, or slower than average pace range. Now I know almost exactly (like +/- 2 minutes) how long I'll take between aid stations, which in turn allows me to carry the right amount of water and calories between each. So I don't use my pace chart to pace, I use it to predict times within the race and find it super useful.

I use my heart rate monitor and how I feel to pace: those are methods that actually do relate to optimizing your performance throughout the event.

1) Early in races (first 10-20%) to help keep you from going too fast.

2) 60-80% into the race to know if you need to push to make your goals or just stay consistent and consolidate time.

For any flatish trail or road ultra I'd have A) and B) splits for both cases above.

For something like Western States (old, but far from flat), ignore the "averages" and find people in your ability range who run really "smart" races. The "average" splits for say 24-hours are the combinations of heroes who tried to run 21 and stumbled home in 23:50 and savvy racers who passed 90 people in the last 30 miles and ran 23:00.

Summary: I use pace charts to force myself to slow down the first part of a race

I agree with Alex about using pace to keep from going out too fast and save something for the end. Other than that, our daily lives are so filled with demands, appointments, deadlines, technology, and expectations, I prefer to eschew most of that in running and just run free. Probably easier said as a mid-packer who isn't plannning to break any records, just out for for a long day of pleasure and pain on the trail.

I like to use pretty intricate pace charts (taking into account distance and elevation loss between aid stations) to approximate a best case scenario and a more probable scenario. This allows my crew to know approximately when to expect me. it also helps me plan what to carry between stations (hand bottle or bladder pack, how many gels, etc.). I also use it to stay conservative early in races, although I aspire to some day "race" an ultra instead of just running them.